Inverse Laplace Transform help

Hi guys, I'm getting a headstart on my uni course starting in Fall, and have started reading the maths book we will be using. I'm currently on the Laplace Transform chapter - I haven't really had much trouble doing the questions so far, except when I reached the following:

Re: Inverse Laplace Transform help

Re: Inverse Laplace Transform help

Exactly! I also tried wolfram to try to understand how to do it - but the answer on there is more confusing!

This question is a maths book from our uni for the upcoming year.

The transfer function I posted on the 1st post is for a 3rd order Bessel filter. And The question asks to find the impulse response h(t). The impulse response h(t) of H(s) is the inverse laplace transform of H(s), which is what I've been trying to do for a good day or so now.